Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
#define rep(i, n) for (int i=0; i<(n); i++)
using namespace std;

const int dx[4]={1,-1,0,0};
const int dy[4]={0,0,1,-1};

int main() {
  int h,w; cin>>h>>w;
  vector<vector<char>> G(h, vector<char>(w));
  rep(i, h) rep(j, w) cin>>G[i][j];

  vector<vector<int>> Dist(h, vector<int>(w, -1));
  queue<pair<int, int>> Que;
  Dist[0][0]=0;
  Que.push(make_pair(0, 0));
  while (!Que.empty()) {
    pair<int, int> P=Que.front();
    Que.pop();
    int x=P.first, y=P.second;
    rep(i, 4) {
      int nx=x+dx[i],ny=y+dy[i];
      if (nx<0||nx>=h||ny<0||ny>=w) continue;
      if (Dist[nx][ny]!=-1) continue;
      if (G[nx][ny]!='.') continue;
      Dist[nx][ny]=Dist[x][y]+1;
      Que.push(make_pair(nx, ny));
    }
  }
  int res=0;
  rep(i, h) rep(j, w) if (G[i][j]=='.') res++;
  if (Dist[h-1][w-1]==-1) cout<<-1<<endl;
  else cout<<res-Dist[h-1][w-1]-1<<endl;
}